Premixed burners known from the state of the art have a swirl chamber and a lance for introducing a fuel into the swirl chamber.
Traditional swirl chambers can be defined by sector plates connected one beside the other in order to define the swirl chamber having a conical shape.
In addition, between adjacent sector plates, slots with a constant width along the axial span of the swirler are defined for introducing an oxidiser, such as air, into the swirl chamber. With other words, those slots have constant widths in consecutive planes in axial direction, wherein these planes are perpendicular to the central axis of the burner.
Close to the slots, also supply pipes (typically provided with nozzles) for fuel supply are also provided.
These premixed burners proved to have good performances, anyhow the mixture of oxidiser and fuel formed in the swirl chamber in some conditions could not be optimised.
Mixture optimization is very important in a premixed burner, because it influences the quality of the combustion that occurs in a combustion chamber typically connected downstream of the burner (with respect to the combusted gas flow).